The term “daddy long legs” often causes confusion, referring to multiple distinct creatures. While some are indeed spiders, others belong to different groups within the animal kingdom. This article will clarify the scientific differences between the various creatures commonly known by this popular name.
Understanding the Confusion
The common name “daddy long legs” is broadly applied to at least three different types of arthropods. The primary groups are harvestmen (Order Opiliones), which are arachnids but not true spiders; cellar spiders (Family Pholcidae), which are genuine spiders; and crane flies (Order Diptera), which are insects. The shared characteristic of long, slender legs across these disparate groups contributes significantly to this common misidentification.
The Harvestman Not a Spider
Harvestmen (Order Opiliones) are arachnids, but they differ significantly from true spiders. Their bodies appear as a single, fused oval segment, unlike spiders which have two distinct body segments (cephalothorax and abdomen) connected by a narrow waist. Harvestmen possess two eyes, typically located on a raised tubercle, contrasting with spiders that usually have eight eyes.
Harvestmen do not produce silk or spin webs. They also lack venom glands. Their mouthparts, called chelicerae, are small, pincer-like structures used for grasping and tearing food, unlike the fangs found in spiders. Harvestmen are omnivorous scavengers, feeding on small insects, decaying plant matter, fungi, and even bird droppings. They are found in damp, shady environments like forests, under rocks and logs, or in basements.
The Cellar Spider A True Spider
Cellar spiders (Family Pholcidae) are true spiders, possessing the defining characteristics of their order. They have two distinct body segments, a cephalothorax and an abdomen. These spiders also produce silk and construct irregular, messy webs, often found in corners of rooms, basements, and other sheltered indoor locations.
Cellar spiders have fangs and venom glands, which they use to immobilize their prey. Their extremely long, thin legs are a distinguishing feature, allowing them to wrap prey in silk from a safe distance. They are predatory, consuming various small arthropods, including insects like mosquitoes and flies, and other spiders. Cellar spiders are found globally and are common in homes.
Dispelling Common Myths
A persistent myth suggests that “daddy long legs” possess the world’s most potent venom but cannot bite humans due to short fangs. This is untrue for both harvestmen and cellar spiders. Harvestmen do not produce venom at all, as they lack venom glands. Their mouthparts are designed for tearing food, not injecting toxins.
Cellar spiders do have venom, but it is not medically significant or dangerous to humans. While they can bite, instances of bites are rare. The effects of a cellar spider bite are mild. Neither harvestmen nor cellar spiders pose a threat to human health, despite widespread misinformation.